In dentistry, an implant means an artificial tooth substituting for a lost natural tooth or a dental procedure that is conducted in such a manner that a fixture is implanted into a jawbone to be fused with the jawbone for a predetermined period, and prostheses such as a coupling member, artificial teeth, and the like are then fixed thereon so that the original functions of teeth can be recovered.
Although a typical prosthetic appliance or a typical false tooth damages surrounding teeth or bones according to the elapse of the time, an implanted tooth does not damage a surrounding tooth structure, and performs the function of an original tooth in the same shape as that of the original tooth. In addition, the implanted tooth is not decayed, so that the implanted tooth can be used for a long time.
Also, implants may facilitate the recovery of a single missing tooth and improve the function of an artificial tooth for a partially or completely edentulous patient, and may improve dental prosthesis recovery in terms of aesthetics. Furthermore, implants disperse an excessive stress applied on tissues of a support bone therearound, and contribute to stabilization of teeth in a row.
In the case of such an implant, a fixture implanted into a jawbone is coupled with a coupling part of an abutment with an upper axial hole of the fixture, and prosthesis is fixed on an upper part of the abutment.
In a conventional implant structure, a fixture and an abutment are thread-coupled, or a coupling hole of the fixture and a coupling protrusion of the abutment are elastically and complementarily coupled.
In a conventional thread-coupled structure, when a continuous load is repeatedly generated within the mouth as an implant wearer chews food, the screw coupling state becomes loose by being rotated since the screw slightly vibrates, and the oscillation width is gradually increased. Accordingly, a gap between the fixture and the abutment is generated. In other words, the artificial tooth shakes, thus the implant user may not easily chew the food, and undesirable mastication pressure may occur around the artificial tooth.
In addition, in the conventional implant structure, as described above, when coupling the abutment with the fixture, a thread-coupling may be performed while an accurate coupling position is not found. Accordingly, the artificial tooth and the alveolar bone may be damaged.
In addition, an implant unit having the above conventional implant structure has many difficulties in coupling the screw within a narrow oral cavity. Particularly, in the case of a patient whose surgical area is located on the back teeth side or who cannot widen his or her mouth widely, the implant procedure becomes more difficult.
As a conventional technique for solving such conventional problems, a dental implant of Korean Patent No. 10-0668368 has been proposed.
In the conventional technique, a dental implant includes: a fixture having an axial hole in an upper portion thereof and implanted into a jawbone; and an abutment having coupling legs made of a shape memory alloy, the legs being inserted into the axial hole of the fixture in a lower portion thereof and elastically coupled with the fixture so that teeth can be used to chew food. Herein, in the conventional technique, a coupling hole of the fixture formed with a concave form in an axial hole inner surface is formed in a vertical surface of the fixture inner surface.
Elastic coupling structures between the fixture and the abutment of the conventional technique have realized much technical advancement by effectively improving the thread-coupling problems. In addition, in actual use, it is very convenient to use since the coupling protrusion of the coupling leg is automatically and elastically coupled with the coupling hole of the fixture when the abutment is inserted within the fixture.
However, the above elastic coupling structures between the fixture and the abutment of the conventional technique cause inconvenience when separating the abutment from the fixture, and are not able to effectively perform buffer functions when vertical occlusal force is applied.
In other words, in order to separate the abutment from the fixture, the abutment is upwardly pulled with respect to the fixture by force such that the coupling protrusion or the coupling hole formed in the coupling leg is detached from the coupling hole or the coupling protrusion that is formed in the axial hole inner surface of the fixture in association by being upwardly pulled, or the abutment is separated from the fixture by rotating the abutment with respect to the fixture and upwardly pulling the fixture.
However, upwardly pulling the abutment with respect to the fixture by force as described above may apply large force to the alveolar bone of the patient through the fixture. As a result, there is great risk of damaging the alveolar bone of the patient due to excessive force. In addition, the associated coupling part and the coupling part which are configured with the coupling protrusion and the coupling hole formed in the abutment and the axial hole inner surface of the fixture become worn down due to repeated attachments and detachments, thus coupling force is reduced. Further, there is a problem in placing an extracting device that separates the abutment from the fixture by separating in a vertical direction, and which is disclosed in Korean Patent No. 10-1309417 and used when an upper surface of the fixture is deeply implanted in a gum.
As another coupling example, in an implant in which a coupling hole with a concave form is formed at positions spaced apart from each other at regular angles (for example, 90 degrees) along a circumferential direction from a predetermined vertical position of a fixture axial hole inner surface, and a coupling protrusion is complementarily formed in a lower part of the abutment in association with the coupling hole are formed (Korean Patent No. 10-0668368), when separating the abutment from the fixture, the abutment is separated from the fixture by rotating the abutment with respect to the fixture in a circumferential direction, separating the coupling protrusion of the abutment from the coupling hole formed in the fixture axial hole inner surface at a predetermined vertical position, and upwardly pulling the abutment from the fixture by force. Herein, sine the size of the implant is small, it is not easy to detect an accurate rotation amount so as to know how much to rotate and then pull it upwards. In some cases, there is a situation that it is re-fastened by being excessively rotated by giving too much power. Although a proper rotation is successfully performed, a considerable force must be applied again in the vertical direction. Further, an effective buffering function for vertical occlusal force may not be performed.
Accordingly, in order to prevent the above problems, it is preferable to use a structure in which a coupling part is separated without being re-coupled by the excessive rotation when the abutment is rotated with respect to the fixture in a circumferential direction or perimeter direction, and the abutment is separated from the fixture by upwardly pulling the abutment with less force. However, in the conventional technique, it is impossible to perform a natural separation process between the abutment and the fixture.
In addition, in the conventional technique described above, the operator may require a large force to upwardly pull the abutment with respect to the fixture y force, and such a procedure may act as a considerable mental burden on the implant procedure.
In addition, in the conventional technique described above, the implant structure may perform a buffer function for horizontal pressure, but a buffer function for vertical occlusion pressure may not be performed. Accordingly, there is a need for a structure that effectively performs a buffer function for vertical occlusion pressure. In addition, in the conventional technique described above, in order to separate the abutment from the fixture without damaging the fixture or the abutment, or the alveolar bone, an extraction device disclosed in Korean Patent No. 10-1309417 should be used. However, when the fixture is deeply implanted from the upper part of the alveolar bone, the extraction device may not be used.